The present invention relates to the field of mass spectrometry.
In mass spectrometers ion sources require heating to high temperatures in order to provide optimum performance from the ion source. Similarly, gas flows are required to aid the ionisation of analytes within the instrument. Often the gas flows are required to be at high temperatures in order to optimise the ionisation of the analytes within the instrument.
In order to provide the required gas flows, at the required temperatures, a heater is required to heat the flow of gas provided to the ion source. Sensors and control mechanisms are placed in the apparatus to measure and control the gas flow to the ion source, and the temperature of the heater that the flow is subjected to.
An example of a conventional gas flow sensor is described in the document “Mass Flow/Pressure meters and controllers for gases and liquids” (Bronkhorst). This document discloses a gas flow sensor comprising two spaced temperature sensors, where the difference in temperature between the two sensors is used to determine a gas flow. If there is no gas flow then both temperature sensors will register the same temperature. When a gas flow is present, a temperature profile develops between the two sensors, which can be used to determine the gas flow.
Increasingly, mass spectrometer manufacturers are trying to reduce the costs involved in the manufacture of instruments, whilst producing reliable, accurate and efficient instruments, which are easy to use. One particularly desirable feature is self contained diagnostics which will automatically alert the user in the event of failures.
However, gas flow sensors to monitor the gas flow, such as the gas flow sensor described in Bronkhurst, can be expensive, which leads to higher cost for the design of instruments.
It is therefore desirable to provide a system for monitoring a gas flow which does not require expensive sensors, yet does allow self contained, automatic alert systems in the event of a failure within the gas flow to the ion source of the mass spectrometer.
It is desired to provide an improved mass spectrometer.